Closing assemblies of this type for a blade ring of a turbomachine are known in various design embodiments in the prior art and serve for closing a blade ring which is attached to a blade support, in particular a rotor disk, of a turbomachine.
Turbomachines are used as working machines or power generation machines. As working machines, said turbomachines serve for setting fluids in motion by generating a flow. As power generation machines, said turbomachines are employed when the kinetic energy of a fluid flow is to be converted to another form of energy, for example electrical energy. Depending on the type of fluid, on the flow direction of the energy, and on the construction of the turbomachines, a differentiation is made between propellers, ventilators, compressors, and jet engines, the former being working machines, and between wind power plants, water turbines, steam turbines, and gas turbines, which are to be considered power generation machines.
Such turbomachines always comprise at least one rotor disk which is held in a rotationally fixed manner on a shaft and conjointly with said shaft forms a rotor. A plurality of blades is usually disposed and held on an external circumferential face of the rotor disk in such a manner that the blades protrude outward in the radial direction. The blades have platforms with engagement elements disposed thereon, said engagement elements being inserted into a T-groove that encircles the circumferential face and being fixed in the radial direction in said T-groove.
It is usual for a blade ring that encircles the rotor disk to be formed in such a manner that two adjacent blades are always mutually spaced apart by an intermediate piece. However, for reasons of space, a normal integral intermediate piece can no longer be inserted into the intermediate space between the first inserted blade and the last inserted blade. Instead, this gap is filled by a closing assembly which in the circumferential direction has the same extent as an intermediate piece but is not configured in an integral manner but comprises a plurality of components that are releasably interconnectable.
A closing assembly of the type mentioned at the outset is known from U.S. Pat. No. 7,435,055 B2. Said closing assembly comprises two insert elements which have a C-shaped basic shape and are configured in such a manner that said insert elements can encompass the webs of the encircling T-groove. The closing assembly furthermore comprises an intermediate element which can be positioned between the two insert elements so as to prevent the latter from moving toward the center of the T-groove. The intermediate element is retained between the insert elements by a locking ring. To this end, the locking ring is connected to a positioning means which penetrates a through bore of the intermediate element and adjacent to the groove base engages in respective recesses of the insert elements.
In order for this closing assembly to be assembled, the two insert elements are first inserted into the T-groove in such a manner that said insert elements in each case encompass one web of the T-groove. The positioning means is then introduced into the T-groove between the two insert elements until said positioning means comes to bear on the groove base. The positioning means is brought to engage with the recesses of the insert elements by rotation. In a next step, the intermediate element is inserted completely into the intermediate space between the insert elements, wherein the positioning means is received in the bore of the intermediate element. On account of the inserted intermediate element, the positioning means is prevented from rotating about the longitudinal axis thereof such that said positioning means is captively engaged in the recesses of the insert elements. Finally, the locking ring is plug-fitted onto the free end of the positioning means. On account thereof, the intermediate element is fixedly held in the position thereof between the insert elements.
When the locking ring is released in the operation of the turbomachine, the intermediate element on account of the acting centrifugal force is ejected from the T-groove such that said intermediate element can no longer prevent the positioning means from rotating about the longitudinal axis thereof. When the positioning means thereafter by virtue of vibrations and on account of rotation loses the engagement thereof in the recesses of the insert elements, said positioning means is likewise ejected from the T-groove such that the two insert elements are no longer fixedly held in the positions thereof and in turn can leave the T-groove. The turbomachine can be damaged by the ejected elements of the closing assembly per se and as a result of the loss of the closure of the blade ring, this having the consequence of corresponding downtime.